Objective-To determine if cardiac dimensions were different in girls with Turner syndrome (TS) that did receive growth hormone (GH) vs. those who did not receive GH.Study design-This was a retrospective, cross sectional study analyzing echocardiograms in 86 females with TS divided into GH-treated (n=67) vs. untreated (n=19) groups. These were subjects with TS participating in the National Institutes of Health protocol between 2001 and 2006.Results-The average age was 16.2 years (range 10-25 yrs) and duration of GH treatment was 4.4 (range 1-14 yrs). The GH-treated group was taller by ∼6 cm (P=0.004) but, cardiac dimensions normalized to body surface area (BSA), including septal and posterior wall thicknesses, left ventricular (LV) mass and LV internal diameters, were not significantly different in the two groups. The fractional shortening index was similar in the two groups. Multiple regression analyses indicated that BSA, but not duration of GH treatment predicted LV dimensions in girls with TS.Conclusions-GH treatment of girls with TS increases stature but does not disproportionately affect cardiac dimensions. Keywords echocardiography; growth hormone; cardiac dimensions; Turner Syndrome All correspondence to: Lea Ann Matura, CRC 10 Center Dr, NIH,, Bethesda, MD 20892, maturale@mail.nih.gov Disclosures: The authors have nothing to disclose and there are no conflict of interests. There is no potential conflict of interest, real or perceived, by the authors. The study was supported by a NIH grant. Lea Ann Matura wrote the first draft of the manuscript no honorarium, grant, or other form of payment was given to anyone to produce the manuscript.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Turner syndrome (45,X, TS) is the most common chromosomal disorder in females, occurring in ∼1/2500 live female births (1). Short stature and ovarian failure are the most prevalent findings, but the most medically significant feature is congenital heart disease with a high risk for aortic dilatation and dissection(2-4). In addition to anatomical defects, recent studies have demonstrated electrocardiographic abnormalities and evidence of autonomic and diastolic dysfunction in individuals with TS suggesting a more extensive involvement of the cardiovascular system than previously appreciated (5-8). Although girls with short stature in the context of TS are not usually growth hormone (GH) deficient, the FDA has approved treatment of these girls with recombinant human GH to augment adult height (9-12). Girls with TS are typically treated with GH for ∼5 years using pharmacological d...